Method for transmitting and receiving uplink signal, user equipment, and base station

ABSTRACT

A method for receiving, by a base station, uplink signals from a user equipment, the method includes transmitting, by the base station, a physical downlink control channel (PDCCH) carrying an uplink grant for a scheduled cell, which is one of a plurality of serving cells for the user equipment, through a scheduling cell among the plurality of serving cells; and receiving, by the base station, a physical uplink shared channel (PUSCH) carrying uplink data of the user equipment through the scheduled cell according to the uplink grant, wherein the user equipment is configured with at least a primary cell (PCell) group and a secondary cell (SCell) group, wherein the PCell group is configured with a PCell and zero or more SCells among the plurality of serving cells, and the SCell group is configured with one or more SCells not belonging to the PCell group among the plurality of serving cells.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a Continuation of U.S. patent application Ser. No.15/333,943 filed on Oct. 25, 2016, which is a Continuation of U.S.patent application Ser. No. 14/125,478 filed on Dec. 11, 2013 (now U.S.Pat. No. 9,491,740 issued on Nov. 8, 2016), which is the National Phaseof PCT/KR2012/005131 filed on Jun. 28, 2012, which claims the benefitunder 35 U.S.C. §119(e) to U.S. Provisional Application No. 61/501,786filed on Jun. 28, 2011, all of which are hereby expressly incorporatedby reference into the present application.

BACKGROUND OF THE INVENTION

Field of the Invention

The present invention relates to a wireless communication system. Moreparticularly, the present invention provides a method and apparatus formore effectively transmitting/receiving an uplink/downlink signal in acarrier aggregation environment in which a plurality of cells isconfigured.

Discussion of the Related Art

A general wireless communication system transmits/receives data throughone downlink (DL) band and through one uplink (UL) band corresponding tothe DL band (in the case of frequency division duplex (FDD) mode), ordivides a prescribed radio frame into a UL time unit and a DL time unitin the time domain and transmits/receives data through the UL/DL timeunit (in the case of time division duplex (TDD) mode). A base station(BS) and a user equipment (UE) transmit and receive data and/or controlinformation scheduled on a prescribed time unit basis, i.e. on asubframe basis. The data is transmitted and received through a dataregion configured in a UL/DL subframe and the control information istransmitted and received through a control region configured in theUL/DL subframe. To this end, various physical channels carrying radiosignals are formed in the UL/DL subframe.

Meanwhile, to use a wider frequency band in recent wirelesscommunication systems, introduction of carrier aggregation (or bandwidthaggregation) technology that uses a wider UL/DL bandwidth by aggregatinga plurality of UL/DL frequency blocks has been discussed.

FIG. 1 illustrates an example of performing communication in amulticarrier environment.

A multicarrier system or carrier aggregation (CA) system refers to asystem for supporting a wide bandwidth by aggregating a plurality ofcarriers each having a narrower bandwidth than a target bandwidth. A CAsystem is different from an orthogonal frequency division multiplexing(OFDM) system in that DL or UL communication is performed using aplurality of carrier frequencies, whereas the OFDM system carries a basefrequency band divided into a plurality of orthogonal subcarriers on asingle carrier frequency to perform DL or UL communication. When aplurality of carriers each having a narrower bandwidth than a targetbandwidth is aggregated, the bandwidth of each of the aggregatedcarriers may be limited to a bandwidth used in a legacy system in orderto ensure backward compatibility with the legacy system. For example,the legacy LTE system supports bandwidths of 1.4, 3, 5, 10, 15, and 20MHz and an LTE-Advanced (LTE-A) system evolved from the LTE system maysupport a bandwidth wider than 20 MHz using only bandwidths supported inthe LTE system. Alternatively, CA may be supported by defining a newbandwidth irrespective of the bandwidths used in the legacy system. Theterm multicarrier is used interchangeably with the term CA or bandwidthaggregation. Contiguous CA and non-contiguous CA are collectivelyreferred to as CA. For reference, when only one component carrier (CC)is used for communication in TDD or when only one UL CC and one DL CCare used for communication in FDD, this corresponds to single carriercommunication (non-CA).

SUMMARY OF THE INVENTION

In a multi-carrier aggregation environment in which a plurality ofcarriers is aggregated to be used in communication between a BS and aUE, a communication method using a single carrier cannot be applied tocommunication using multiple carriers. A new communication methodsuitable for communication using multiple carriers while minimizinginfluence on a legacy system should be defined.

The technical objects that can be achieved through the present inventionare not limited to what has been particularly described hereinabove andother technical objects not described herein will be more clearlyunderstood by persons skilled in the art from the following detaileddescription.

According to an aspect of the present invention, provided herein is amethod for transmitting, by a user equipment configured with a pluralityof cells, an uplink signal to a base station. The method comprises:configuring a primary cell (PCell) group including at least a PCellamong the plurality of cells and a secondary cell (SCell) groupincluding one or more SCells among the plurality of cells; andtransmitting uplink control information regarding the SCell group to thebase station on a physical uplink control channel (PUCCH) or a physicaluplink shared channel (PUSCH), wherein the PUCCH is transmitted to thebase station using an SCell configured as an anchor SCell among the oneor more SCells of the SCell group and the PUSCH is transmitted to thebase station using one SCell among the one or more SCells of the SCellgroup.

In another aspect of the present invention, provided herein is a userequipment for transmitting an uplink signal to a base station, whereinthe user equipment is configured with a plurality of cells. The userequipment comprises: a radio frequency (RF) unit; and a processorconfigured to control the RF unit, wherein the processor configures aprimary cell (PCell) group including at least a PCell among theplurality of cells and a secondary cell (SCell) group including one ormore SCells among the plurality of cells and controls the RF unit totransmit uplink control information regarding the SCell group to thebase station on a physical uplink control channel (PUCCH) or a physicaluplink shared channel (PUSCH), and wherein the PUCCH is transmitted tothe base station using an SCell configured as an anchor SCell among theone or more SCells of the SCell group and the PUSCH is transmitted tothe base station using one SCell among the one or more SCells of theSCell group.

In another aspect of the present invention, provided herein is a methodfor transmitting, by a user equipment configured with a plurality ofcells, an uplink signal to a base station. The method comprises:configuring a primary cell (PCell) group including at least a PCellamong the plurality of cells and a secondary cell (SCell) groupincluding one or more SCells among the plurality of cells; and receivinguplink control information regarding the SCell group from the userequipment on a physical uplink control channel (PUCCH) or a physicaluplink shared channel (PUSCH), wherein the PUCCH is received from theuser equipment using an SCell configured as an anchor SCell among theone or more SCells of the SCell group and the PUSCH is received from theuser equipment using one SCell among the one or more SCells of the SCellgroup.

In another aspect of the present invention, provided herein is a userequipment for transmitting an uplink signal to a base station, whereinthe user equipment is configured with a plurality of cells. The userequipment comprises: a radio frequency (RF) unit; and a processorconfigured to control the RF unit, wherein the processor configures aprimary cell (PCell) group including at least a PCell among theplurality of cells and a secondary cell (SCell) group including one ormore SCells among the plurality of cells and controls the RF unit toreceive uplink control information regarding the SCell group from theuser equipment on a physical uplink control channel (PUCCH) or aphysical uplink shared channel (PUSCH), and wherein the PUCCH isreceived from the user equipment using an SCell configured as an anchorSCell among the one or more SCells of the SCell group and the PUSCH isreceived from the user equipment using one SCell among the one or moreSCells of the SCell group.

In each aspect of the present invention, if a transmission timing of thePUCCH using the anchor SCell in the SCell group collides with atransmission timing of the PUSCH using one SCell in the SCell group, theuplink control information regarding the SCell group may be transmittedto the base station from the user equipment on the PUSCH.

In each aspect of the present invention, if the uplink controlinformation regarding the SCell group is acknowledgement/negativeacknowledgement (ACK/NACK) information regarding the anchor SCell in theSCell group, the PUCCH may be transmitted to the base station from theuser equipment using a PUCCH resource associated with a control channelelement (CCE) of a physical downlink control channel (PDCCH) receivedusing the anchor SCell among PUCCH resources reserved for the anchorSCell.

In each aspect of the present invention, a physical downlink controlchannel (PDCCH) for the SCell group may be received from the basestation and, if the PDCCH carries a downlink grant for the anchor SCell,transmit power of the PUCCH may be determined based on transmit powercontrol (TPC) information in the PDCCH and, if the PDCCH carries adownlink grant for an SCell other than the anchor SCell among the one ormore SCells, a PUCCH resource for transmitting/receivingacknowledgement/negative acknowledgement (ACK/NACK) informationregarding the SCell group may be determined based on the TPCinformation.

In each aspect of the present invention, the anchor SCell may be used totransmit/receive a physical downlink control channel (PDCCH) carrying anuplink grant or a downlink grant for at least one SCell in the SCellgroup.

The above technical solutions are merely some parts of the embodimentsof the present invention and various embodiments into which thetechnical features of the present invention are incorporated can bederived and understood by persons skilled in the art from the followingdetailed description of the present invention.

According to the present invention, UL carriers on which a UE and a BSoperate in different frequencies and/or UL carrier(s) on which the UEand the BS operate in a frequency using antennas of different locationscan be aggregated.

According to the present invention, a plurality of time synchronizationscan be efficiently managed with respect to one UE.

According to the present invention, different time synchronizations canbe applied to UL CCs having different frequency characteristics.

According to the present invention, DL/UL control information can beefficiently transmitted/received in a CA environment and a cross-carrierscheduling environment.

Effects according to the present invention are not limited to what hasbeen particularly described hereinabove and other advantages notdescribed herein will be more clearly understood by persons skilled inthe art from the following detailed description of the presentinvention.

BRIEF DESCRIPTION OF THE DRAWINGS

The accompanying drawings, which are included to provide a furtherunderstanding of the invention, illustrate embodiments of the inventionand together with the description serve to explain the principle of theinvention.

FIG. 1 illustrates an example of performing communication in amulticarrier environment.

FIG. 2 illustrates the structure of a radio frame used in a wirelesscommunication system.

FIG. 3 illustrates the structure of a downlink (DL)/uplink (UL) slot ina wireless communication system.

FIG. 4 illustrates the structure of a DL subframe used in a 3GPP LTE(-A)system.

FIG. 5 illustrates the structure of a UL subframe used in a 3GPP LTE(-A)system.

FIG. 6 is a diagram explaining the meaning of a cell in 3GPP LTE(-A).

FIGS. 7 and 8 illustrate embodiments of the present invention.

FIG. 9 is a block diagram illustrating elements of a transmitting device10 and a receiving device 20 for implementing the present invention.

DETAILED DESCRIPTION OF THE EMBODIMENTS

The following embodiments are combinations of elements and features ofthe present invention in a predetermined form. The elements or featuresmay be considered selective unless mentioned otherwise. Each element orfeature may be practiced without being combined with other elements orfeatures. Further, an embodiment of the present invention may beconstructed by combining parts of the elements and/or features.Operation orders described in embodiments of the present invention maybe rearranged. Some constructions of any one embodiment may be includedin another embodiment and may be replaced with correspondingconstructions of another embodiment.

In some instances, well-known structures and devices may be omitted inorder to avoid obscuring the concepts of the present invention and theimportant functions of the structures and devices may be shown in blockdiagram form. The same reference numbers will be used throughout thedrawings to refer to the same or like parts.

The following technique can be used for a variety of radio accesssystems, for example, code division multiple access (CDMA), frequencydivision multiple access (FDMA), time division multiple access (TDMA),orthogonal frequency division multiple access (OFDMA), single carrierfrequency division multiple access (SC-FDMA), and the like. CDMA may beembodied through radio technology such as universal terrestrial radioaccess (UTRA) or CDMA2000. TDMA may be embodied through radio technologysuch as global system for mobile communications (GSM)/general packetradio service (GPRS)/enhanced data rates for GSM evolution (EDGE). OFDMAmay be embodied through radio technology such as institute of electricaland electronics engineers (IEEE) 802.11 (Wi-Fi), IEEE 802.16 (WiMAX),IEEE 802-20, and evolved UTRA (E-UTRA). UTRA is a part of a universalmobile telecommunications system (UMTS). 3rd generation partnershipproject (3GPP) long term evolution (LTE) is part of evolved UMTS(E-UMTS) using E-UTRA. 3GPP LTE employs OFDMA in DL and employs SC-FDMAin UL. LTE-advanced (LTE-A) is an evolved version of 3GPP LTE. WiMAX canbe explained by IEEE 802.16e (WirelessMAN-OFDMA reference system) andadvanced IEEE 802.16m (WirelessMAN-OFDMA advanced system). For clarity,the following description focuses on 3GPP LTE(-A) standards. However,technical features of the present invention are not limited thereto.

The embodiments of the present invention can be supported by standarddocuments disclosed in at least one of wireless access systems includingan IEEE 802 system, a 3GPP system, a 3GPP LTE system, a 3GPP LTE-Asystem, and a 3GPP2 system. In particular, steps or parts, which are notdescribed to clearly reveal the technical idea of the present invention,in the embodiments of the present invention may be supported by theabove documents. All terminology used herein may be supported by theabove-mentioned documents.

Specific terms used in the following description are proposed to aid inunderstanding the present invention, and the use of these specific termsmay be changed to another format within the technical scope or spirit ofthe present invention.

In the embodiments of the present invention, a description is given of adata transmission and reception relationship between a base station (BS)and a user equipment (UE). Here, the ‘base station (BS)’ refers to aterminal node of a network communicating directly with the UE. The BSexchanges data and control information by communicating with the UE. Insome cases, a specific operation described as being performed by the BSin this specification may be performed by an upper node of the BS. Inother words, it is apparent that, in a network comprised of a pluralityof network nodes including the BS, various operations performed forcommunication with the UE may be performed by the BS, or network nodesother than the BS. The term ‘base station (BS)’ may be replaced withterms such as fixed station, Node B, eNode B (eNB), access point (AP),etc. The ‘user equipment (UE)’ may be fixed or may have mobility.Examples of the UE include various devices that transmit and receiveuser data and/or various kinds of control information to and from a BS.The term ‘user equipment (UE)’ may be replaced with terms such asterminal, mobile station (MS), mobile subscriber station (MSS),subscriber station (SS), etc.

In the present invention, a physical downlink control channel (PDCCH)and a physical downlink shared channel (PDSCH) refer to a set oftime-frequency resources or resource elements (REs) carrying downlinkcontrol information (DCI) and a set of time-frequency resources or REscarrying DL data, respectively. In addition, a physical uplink controlchannel (PUCCH), a physical uplink shared channel (PUSCH), and aphysical random access channel (PRACH) refer to a set of time-frequencyresources or REs carrying uplink control information (UCI), a set oftime-frequency resources or REs carrying uplink data, and a set oftime-frequency resources or REs carrying a random access signal,respectively. In the present invention, PUCCH/PUSCH/PRACH transmissionof a UE is conceptually identical to UCI/UL data/random access signaltransmission on PUSCH/PUCCH/PRACH, respectively. In addition,PDCCH/PDSCH transmission of a BS is conceptually identical to DLdata/DCI transmission on PDCCH/PDSCH, respectively.

FIG. 2 illustrates the structure of a radio frame used in a wirelesscommunication system. Specifically, FIG. 2(a) illustrates an exemplarystructure of a radio frame which can be used in FDD in 3GPP LTE(-A) andFIG. 2(b) illustrates an exemplary structure of a radio frame which canbe used in TDD in 3GPP LTE(-A).

Referring to FIG. 2, a 3GPP LTE(-A) radio frame is 10 ms (307,200T_(s))in duration. The radio frame is divided into 10 subframes of equal size.Subframe numbers may be assigned to the 10 subframes within one radioframe, respectively. Here, T_(s) denotes sampling time whereT_(s)=1/(2048*15 kHz). Each subframe is 1 ms long and is further dividedinto two slots. 20 slots are sequentially numbered from 0 to 19 in oneradio frame. Duration of each slot is 0.5 ms. A time interval in whichone subframe is transmitted is defined as a transmission time interval(TTI). Time resources may be distinguished by radio frame number (orradio frame index), subframe number (or subframe index), slot number (orslot index), and the like.

A radio frame may have different configurations according to duplexmode. In FDD mode for example, since DL transmission and UL transmissionare discriminated according to frequency, a radio frame for a specificfrequency band operating on a prescribed carrier frequency includeseither DL subframes or UL subframes. In TDD mode, since DL transmissionand UL transmission are discriminated according to time, a radio framefor a specific frequency band operating on a prescribed carrierfrequency includes both DL subframes and UL subframes.

Table 1 shows an exemplary UL-DL configuration within a radio frame inTDD mode.

TABLE 1 Downlink-to- DL-UL Uplink switch- configu- point Subframe numberration periodicity 0 1 2 3 4 5 6 7 8 9 0 5 ms D S U U U D S U U U 1 5 msD S U U D D S U U D 2 5 ms D S U D D D S U D D 3 10 ms D S U U U D D D DD 4 10 ms D S U U D D D D D D 5 10 ms D S U D D D D D D D 6 5 ms D S U UU D S U U D

In Table 1, D denotes a DL subframe, U denotes a UL subframe, and Sdenotes a special subframe. The special subframe includes three fields,i.e. a downlink pilot time slot (DwPTS), a guard period (GP), and anuplink pilot time slot (UpPTS). DwPTS is a time slot reserved for DLtransmission and UpPTS is a time slot reserved for UL transmission.Table 2 shows an example of the special subframe configuration.

TABLE 2 Normal cyclic prefix in downlink Extended cyclic prefix indownlink Special UpPTS UpPTS subframe Normal cyclic Extended cyclicDwPTS Normal cyclic Extended cyclic configuration DwPTS prefix in uplinkprefix in uplink ee prefix in uplink prefix in uplink 0  6592 · T_(s)2192 · T_(s) 2560 · T_(s)  7680 · T_(s) 2192 · T_(s) 2560 · T_(s) 119760 · T_(s) 20480 · T_(s) 2 21952 · T_(s) 23040 · T_(s) 3 24144 ·T_(s) 25600 · T_(s) 4 26336 · T_(s)  7680 · T_(s) 4384 · T_(s) 5120 ·T_(s) 5  6592 · T_(s) 4384 · T_(s) 5120 · T_(s) 20480 · T_(s) 6 19760 ·T_(s) 23040 · T_(s) 7 21952 · T_(s) — — — 8 24144 · T_(s) — — —

FIG. 3 illustrates the structure of a DL/UL slot structure in a wirelesscommunication system. In particular, FIG. 3 illustrates the structure ofa resource grid of a 3GPP LTE(-A) system. One resource grid exists perantenna port.

Referring to FIG. 3, a slot includes a plurality of OFDM symbols in thetime domain and includes a plurality of resource blocks (RBs) in thefrequency domain. The OFDM symbol may refer to one symbol duration.Referring to FIG. 3, a signal transmitted in each slot may be expressedby a resource grid including N^(DL/UL) _(RB)*N^(RB) _(sc) subcarriersand N^(DL/UL) _(symb) OFDM symbols. N^(DL) _(RB) denotes the number ofRBs in a DL slot and N^(UL) _(RB) denotes the number of RBs in a ULslot. N^(DL) _(RB) and N^(UL) _(RB) depend upon DL transmissionbandwidth and UL transmission bandwidth, respectively. N^(DL) _(symb)denotes the number of OFDM symbols in a DL slot, N^(UL) _(symb) denotesthe number of OFDM symbols in a UL slot, and N^(RB) _(sc) denotes thenumber of subcarriers configuring one RB.

An OFDM symbol may be referred to as an OFDM symbol, an SC-FDM symbol,etc. according to a multiple access scheme. The number of OFDM symbolsincluded in one slot may be varied according to channel bandwidth and CPlength. For example, in a normal cyclic prefix (CP) case, one slotincludes 7 OFDM symbols. In an extended CP case, one slot includes 6OFDM symbols. Although one slot of a subframe including 7 OFDM symbolsis shown in FIG. 3 for convenience of description, embodiments of thepresent invention are similarly applicable to subframes having adifferent number of OFDM symbols. Referring to FIG. 3, each OFDM symbolincludes N^(DL/UL) _(RB)*N^(RB) _(sc) subcarriers in the frequencydomain. The type of subcarrier may be divided into a data subcarrier fordata transmission, a reference signal (RS) subcarrier for RStransmission, and a null subcarrier for a guard band and a DC component.The null subcarrier for the DC component is unused and is mapped to acarrier frequency f₀ in a process of generating an OFDM signal or in afrequency up-conversion process. The carrier frequency is also called acenter frequency.

One RB is defined as N^(DL/UL) _(symb) (e.g. 7) consecutive OFDM symbolsin the time domain and as N^(RB) _(sc) (e.g. 12) consecutive subcarriersin the frequency domain. For reference, a resource composed of one OFDMsymbol and one subcarrier is referred to a resource element (RE) ortone. Accordingly, one RB includes N^(DL/UL) _(symb)*N^(RB) _(sc) REs.Each RE within a resource grid may be uniquely defined by an index pair(k, l) within one slot. k is an index ranging from 0 to N^(DL/UL)_(RB)*N^(RB) _(sc)−1 in the frequency domain, and l is an index rangingfrom 0 to N^(DL/UL) _(symb)−1 in the time domain.

In one subframe, two RBs, each located in each of two slots of thesubframe while occupying the same N^(RB) _(sc) consecutive subcarriers,are referred to as a physical resource block (PRB) pair. Two RBsconfiguring a PRB pair have the same PRB number (or the same PRB index).

FIG. 4 illustrates the structure of a DL subframe used in a 3GPP LTE(-A)system.

Referring to FIG. 4, a DL subframe is divided into a control region anda data region in the time domain. Referring to FIG. 4, a maximum of 3(or 4) OFDM symbols located in a front part of a first slot of asubframe correspond to the control region. Hereinafter, a resourceregion usable for PDCCH transmission in the DL subframe is referred toas a PDCCH region. OFDM symbols other than the OFDM symbol(s) used inthe control region correspond to the data region to which a PDSCH isallocated. Hereinafter, a resource region usable for PDSCH transmissionin the DL subframe is referred to as a PDSCH region. Examples of a DLcontrol channel used in 3GPP LTE include a physical control formatindicator channel (PCFICH), a physical downlink control channel (PDCCH),a physical hybrid ARQ indicator channel (PHICH), etc. The PCFICH istransmitted in the first OFDM symbol of a subframe and carriesinformation about the number of OFDM symbols used for transmission of acontrol channel within a subframe. The PHICH carries a hybrid automaticrepeat request (HARQ) acknowledgement/negative-acknowledgement(ACK/NACK) signal as a response to UL transmission.

Control information transmitted via a PDCCH is referred to as downlinkcontrol information (DCI). The DCI includes resource allocationinformation for a UE or a UE group and other control information. Forexample, the DCI includes transmission format and resource allocationinformation of a DL shared channel (DL-SCH) (hereinafter, DL grant),transmission format and resource allocation information of a UL sharedchannel (UL-SCH) (hereinafter, UL grant), paging information on a pagingchannel (PCH), system information on the DL-SCH, resource allocationinformation of a higher-layer control message such as a random accessresponse transmitted on a PDSCH, a transmit (Tx) power control commandset of individual UEs in a UE group, a Tx power control command,activation indication information of voice over IP (VoIP), a downlinkassignment index (DAI), etc. A PDCCH is transmitted on an aggregate ofone or plural consecutive control channel elements (CCEs). A CCE is alogical assignment unit used to provide coding rate based on a radiochannel state to the PDCCH. The CCE corresponds to a plurality ofresource element groups (REGs). For example, one CCE corresponds to 9REGs and one REG corresponds to 4 REs.

The BS may transmit data to a UE or UE group in the data region. Datatransmitted in the data region is referred to as user data. A PDSCH maybe allocated to the data region for user data transmission. The PCH andthe DL-SCH are transmitted on the PDSCH. A UE may decode controlinformation received on a PDCCH and thus read data received on thePDSCH. The size and usage of DCI transmitted on one PDCCH may varyaccording to DCI format and the size of the DCI may vary according tocoding rate. Information indicating to which UE or UE group PDSCH datais transmitted and information indicating how the UE or UE group shouldreceive and decode the PDSCH data are transmitted on the PDCCH. Forexample, it is assumed that a specific PDCCH is CRC-masked with a radionetwork temporary identity (RNTI) ‘A’ and information about datatransmitted using a radio resource ‘B’ (e.g. frequency location) andusing transport format information ‘C’ (e.g. transmission block size,modulation scheme, coding information, etc.) is transmitted in aspecific DL subframe. Then, the UE monitors the PDCCH using RNTIinformation thereof. The UE having the RNTI ‘A’ receives the PDCCH andreceives the PDSCH indicated by ‘B’ and ‘C’ through information of thereceived PDCCH.

A plurality of PDCCHs may be transmitted in the control region. A UE maymonitor the plurality of PDCCHs to detect a PDCCH thereof. Basically,the UE does not know the location at which a PDCCH thereof istransmitted. Therefore, the UE performs blind detection (also referredto as blind decoding) for all PDCCHs of a corresponding DCI format inevery subframe until a PDCCH having an identifier thereof is received.

FIG. 5 illustrates the structure of a UL subframe used in a 3GPP LTE(-A)system.

Referring to FIG. 5, a UL subframe may be divided into a data region anda control region in the frequency domain. One or several PUCCHs may beallocated to the control region to deliver UCI. One or several PUSCHsmay be allocated to the data region of the UE subframe to deliver userdata. The control region and the data region in the UL subframe may alsobe referred to as a PUCCH region and a PUSCH region, respectively. Asounding reference signal (SRS) may be allocated to the data region. TheSRS is transmitted on the last OFDM symbol of the UL subframe in thetime domain and is transmitted on a data transmission band, that is, adata region, of the UL subframe in the frequency domain. SRSs of severalUEs, which are transmitted/received on the last OFDM symbol of the samesubframe, can be distinguished according to a frequencylocation/sequence.

If a UE employs an SC-FDMA scheme in UL transmission, in a 3GPP LTErelease-8 or release-9 system, a PUCCH and a PUSCH cannot besimultaneously transmitted on one carrier in order to maintain a singlecarrier property. In a 3GPP LTE release-10 system, support/non-supportof simultaneous transmission of the PUCCH and the PUSCH may be indicatedby higher layers.

In the UL subframe, subcarriers distant from a direct current (DC)subcarrier are used as the control region. In other words, subcarrierslocated at both ends of a UL transmission bandwidth are used to transmitUL control information such as ACK/NACK for DL data, channel stateinformation for DL (e.g. a channel quality indicator (CQI), a precodingmatrix index (PMI), a rank indicator (RI), etc.), and a schedulingrequest (SR). A DC subcarrier is a component unused for signaltransmission and is mapped to a carrier frequency f₀ in a frequencyup-conversion process. A PUCCH for one UE is allocated to an RB pairbelonging to resources operating in one carrier frequency and RBsbelonging to the RB pair occupy different subcarriers in two slots. ThePUCCH allocated in this way is expressed by frequency hopping of the RBpair allocated to the PUCCH over a slot boundary. If frequency hoppingis not applied, the RB pair occupies the same subcarriers.

The size and usage of UCI carried by one PUCCH may be changed accordingto PUCCH format and the size of the UCI may be changed according tocoding rate. A UE is assigned PUCCH resources for UCI transmission by aBS through a higher layer signal, a dynamic control signal, or animplicit scheme. Physical resources used for a PUCCH depend upon twoparameters, N⁽²⁾ _(RB) and N⁽¹⁾ _(CS), given by higher layers. Theparameter N⁽²⁾ _(RB), which is equal to or greater than 0 (N⁽²⁾_(RB)≧0), indicates available bandwidth for PUCCH format 2/2a/2btransmission in each slot and is expressed as an integer multiple ofN^(RB) _(SC). The parameter N⁽¹⁾ _(CS) indicates the number of cyclicshifts used for PUCCH format 1/1a/1b in an RB used for a mixture offormats 1/1a/1b and 2/2a/2b. A value of N⁽¹⁾ _(CS) is an integermultiple of Δ^(PUCCH) _(shift) within a range of {0, 1, . . . , 7}.Δ^(PUCCH) _(shift) is provided by higher layers. If N⁽¹⁾ _(CS) is 0, nomixed RBs are present. In each slot, at most one RB supports a mixtureof PUCCH format 1/1a/1b and PUCCH format 2/2a/2b. Resources used fortransmission of PUCCH format 1/1a/1b, PUCCH format 2/2a/2b, and PUCCHformat 3 by an antenna port p are expressed by n^((1,p)) _(PUCCH),n^((2,p)) _(PUCCH)<N⁽²⁾ _(RB)N^(RB) _(sc)+ceil(N⁽¹⁾ _(cs)/8)·(N^(RB)_(sc)−N⁽¹⁾ _(cs)−2), and n^((3,p)) _(PUCCH), respectively, which areindexes of non-negative integers. More specifically, according to aspecific rule predefined for each PUCCH format, an orthogonal sequenceand/or a cyclic shift, to be applied to UCI from PUCCH resource indexes,are determined and resource indexes of two RBs in a subframe, to which aPUCCH is to be mapped, are provided.

For example, a resource for PUCCH format 1a/1b used for transmission ofACK/NACK information for a PDCCH or a PDSCH associated with the PDCCH isimplicitly allocated. An index of the PUCCH resource for PUCCH format1a/1b is determined by linkage with a specific CCE index (e.g. lowestCCE index n_(CCE)) among indexes of CCEs used for transmission of thePDCCH. For instance, in a 3GPP LTE(-A) system, indexes of PUCCH format1a/1b resources for transmission by two antenna ports p₀ and p₁ aredetermined as follows.n _(PUCCH) ^((1,p=p) ⁰ ⁾ =n _(CCE) +N _(PUCCH) ⁽¹⁾  [Equation 1]n _(PUCCH) ^((1,p=p) ¹ ⁾ =n _(CCE)+1+N _(PUCCH) ⁽¹⁾  [Equation 2]

Here, n^((1, p=p0)) _(PUCCH) denotes an index (i.e. number) of a PUCCHresource to be used by antenna port p₀, n^((1, p=p1)) _(PUCCH) denotesan index of a PUCCH resource index to be used by antenna port p₁, andN⁽¹⁾ _(PUCCH) denotes a signaling value received from higher layers.n_(CCE) is the lowest CCE index used for PDCCH transmission.

Meanwhile, as described with reference to FIG. 1, CA or bandwidthaggregation technology has recently been discussed. For example,referring to FIG. 1, five CCs, each of 20 MHz, may be aggregated on eachof UL and DL to support a bandwidth of 100 MHz. The respective CCs maybe contiguous or non-contiguous in the frequency domain. An EvolvedUniversal Terrestrial Radio Access (E-UTRA) operating band of Table 3may be used for, but not limited to, CA.

TABLE 3 Uplink (UL) Downlink (DL) operating band operating band E-UTRABS receive BS transmit Operating UE transmit UE receive Duplex BandF_(UL) _(—) _(low)-F_(UL) _(—) _(high) F_(DL) _(—) _(low)-F_(DL) _(—)_(high) Mode  1 1920 MHz-1980 MHz 2110 MHz-2170 MHz FDD  2 1850 MHz-1910MHz 1930 MHz-1990 MHz FDD  3 1710 MHz-1785 MHz 1805 MHz-1880 MHz FDD  41710 MHz-1755 MHz 2110 MHz-2155 MHz FDD  5 824 MHz-849 MHz 869 MHz-894MHz FDD   6¹ 830 MHz-840 MHz 875 MHz-885 MHz FDD  7 2500 MHz-2570 MHz2620 MHz-2690 MHz FDD  8 880 MHz-915 MHz 925 MHz-960 MHz FDD  9 1749.9MHz-1784.9 MHz 1844.9 MHz-1879.9 MHz FDD 10 1710 MHz-1770 MHz 2110MHz-2170 MHz FDD 11  1427.9 MHz-[1447.9] MHz  1475.9 MHz-[1495.9] MHzFDD 12 699 MHz-716 MHz 729 MHz-746 MHz FDD 13 777 MHz-787 MHz 746MHz-756 MHz FDD 14 788 MHz-798 MHz 758 MHz-768 MHz FDD 15 ReservedReserved FDD 16 Reserved Reserved FDD 17 704 MHz-716 MHz 734 MHz-746 MHzFDD 18 815 MHz-830 MHz 860 MHz-875 MHz FDD 19 830 MHz-845 MHz 875MHz-890 MHz FDD 20 832 MHz-862 MHz 791 MHz-821 MHz 21 1447.9 MHz-1462.9MHz 1495.9 MHz-1510.9 MHz FDD 22 [3410] MHz-[3500] MHz [3510] MHz-[3600]MHz FDD . . . 33 1900 MHz-1920 MHz 1900 MHz-1920 MHz TDD 34 2010MHz-2025 MHz 2010 MHz-2025 MHz TDD 35 1850 MHz-1910 MHz 1850 MHz-1910MHz TDD 36 1930 MHz-1990 MHz 1930 MHz-1990 MHz TDD 37 1910 MHz-1930 MHz1910 MHz-1930 MHz TDD 38 2570 MHz-2620 MHz 2570 MHz-2620 MHz TDD 39 1880MHz-1920 MHz 1880 MHz-1920 MHz TDD 40 2300 MHz-2400 MHz 2300 MHz-2400MHz TDD [41] [3400] MHz-[3600] MHz [3400] MHz-[3600] MHz TDD Note ¹Band6 is not applicable.

For convenience, FIG. 1 shows the case in which the bandwidth of a UL CCis the same as the bandwidth of a DL CC and the two are symmetrical.However, the bandwidth of each CC may be independently determined. It isalso possible to configure asymmetric CA in which the number of UL CCsis different from the number of DL CCs. A UL CC and a DL CC may also bereferred to as UL resources and DL resources, respectively. Even when aBS manages X DL CCs, a frequency bandwidth which can be received by aspecific UE may be limited to Y (≦X) DL CCs. In this case, the UE needsto monitor DL signals/data transmitted through the Y CCs. In addition,even when the BS manages L UL CCs, a frequency bandwidth that can bereceived by a specific UE may be limited to M (≦L) UL CCs. The limitedDL/UL CCs for a specific UE are referred to as serving UL/DL CCsconfigured in the specific UE. The BS may allocate a prescribed numberof CCs to the UE by activating some or all of the CCs managed by the BSor by deactivating some CCs managed by the BS. The BS may change theactivated/deactivated CCs and change the number of activated/deactivatedCCs. Various parameters for CA may be configured cell-specifically, UEgroup-specifically, or UE-specifically. Once the BS allocates availableCCs to the UE cell-specifically or UE-specifically, at least one of theallocated CCs is not deactivated, unless overall CC allocation to the UEis reconfigured or the UE is handed over. Hereinafter, the CC that isnot deactivated unless overall CC allocation to the UE is reconfiguredis referred to as a primary CC (PCC) and a CC that the BS can freelyactivate/deactivate is referred to as a secondary CC (SCC). Singlecarrier communication uses one PCC for communication between the UE andthe BS and does not use the SCC for communication.

Meanwhile, 3GPP LTE(-A) uses the concept of cells to manage radioresources. FIG. 6 is a view explaining the meaning of a cell in 3GPPLTE(-A).

A cell is defined as a combination of DL resources and UL resources,that is, a combination of a DL CC and a UL CC. The cell can beconfigured of DL resources alone, or of both DL resources and ULresources. When CA is supported, a linkage between a carrier frequencyof the DL resources (or DL CC) and a carrier frequency of the ULresources (or UL CC) may be indicated by system information. Forexample, a combination of the DL resources and the UL resources may beindicated by a system information block type 2 (SIB2) linkage.

Referring to FIG. 6(a), for FDD, a UL operating band and a DL operatingband are different. Therefore, for FDD, different carrier frequenciesare linked to constitute one cell and the SIB2 linkage indicates afrequency of a UL CC using a frequency different from a frequency of aDL CC accessed by the UE. In other words, in the case of FDD, a DL CCconstituting one cell and a UL CC linked with the DL CC operate ondifferent frequencies.

Referring to FIG. 6(b), for TDD, a UL operating band and a DL operatingband are the same. Therefore, one carrier frequency constitutes one celland the SIB2 linkage indicates a frequency of a UL CC using the samefrequency as a frequency of a DL CC accessed by the UE. In other words,in the case of TDD, a DL CC constituting one cell and a UL CC linkedwith the DL CC operate on the same frequency.

Here, the carrier frequency refers to a center frequency of each cell orCC. A cell that operates on a primary frequency (or PCC) may be referredto as a primary cell (PCell) or PCC and a cell that operates on asecondary frequency (or SCC) may be referred to as a secondary cell(SCell) or SCC. A PCell refers to a cell used for the UE to perform aninitial connection establishment or connection re-establishmentprocedure. The PCell may also refer to a cell indicated in a handoverprocedure. As another example, the PCell may also refer to a DL CC onwhich the UE receives a DL synchronization signal (SS) to acquireinitial synchronization and a UL CC linked with the DL CC. A carriercorresponding to the PCell in DL is referred to as a DL primary CC (DLPCC) and a carrier corresponding to PCell in UL is referred to as a ULprimary CC (UL PCC). An SCell refers to a cell which can be configuredafter radio resource control (RRC) connection establishment and can beused to provide additional radio resources. According to capabilities ofthe UE, the SCell may form a set of serving cells for the UE togetherwith PCell. The serving cell may be referred to as a serving CC. Acarrier corresponding to the SCell in DL is referred to as a DLsecondary CC (DL SCC) and a carrier corresponding to the SCell in UL isreferred to as a UL secondary CC (UL SCC). For a UE in an RRC_CONNECTEDstate, for which CA is not configured or CA is not supported, only oneserving cell comprised of only a PCell is present. Meanwhile, for a UEin an RRC_CONNECTED state, for which CA is configured, one or moreserving cells may be present and the one or more serving cells mayinclude one PCell and one or more SCells. For CA, a network mayconfigure a UE that supports CA by adding one or more SCells to a PCellinitially configured in the connection establishment procedure after aninitial security activation procedure is initiated. However, even if theUE supports CA, the network may configure only the PCell for the UE,without adding the SCells.

Hereinafter, a cell used for a UE to perform an initial connectionestablishment or connection re-establishment procedure with a network ofa BS, a cell indicated in a handover procedure, or a cell with whichinitial DL synchronization is acquired is referred to as a PCC and theother cells are referred to as SCCs. The PCC may be referred to as ananchor CC or a primary carrier and the SCC may be referred to as anSCell or a secondary CC.

According to current discussion about a 3GPP LTE(-A) system, specificcontrol information may be transmitted/received only through a specificCC. In other words, 3GPP LTE(-A) up to now has specified that the PCC isin charge of DL control signaling, associated with system information(SI) and with common control information (CCI) transmitted/receivedthrough a common search space and in charge of UL control signaling,associated with uplink control information (UCI) includingacknowledgement (ACK)/negative ACK (NACK) for DL data, a channel qualityindicator (CQI), etc. In terms of DL, the SI is transmitted/receivedusing only the PCC and the UE applies SI acquisition only on the PCC. Inaddition, non-access stratum (NAS) mobility information istransmitted/received only on the PCC. Further, the common search space,in which all UEs within a coverage area of a corresponding BS attempt toperform blind detection to detect a PDCCH, is present only on the PCC.In terms of UL, current 3GPP LTE(-A) specifies that UCI carried by aPUCCH should always be transmitted/received using the PCC. Accordingly,if the PCC is configured for the UE, the UE can transmit the PUCCH onlyon the PCC.

Meanwhile, in the case of communication using a single carrier, only oneserving cell is present and thus a PDCCH carrying a UL/DL grant and aPUSCH/PDSCH corresponding to the PDCCH are transmitted in the same cell.In other words, in the case of FDD in a single-carrier environment, aPDCCH for a DL grant with respect to a PDSCH to be transmitted on aspecific DL CC is transmitted on the specific CC and a PDCCH for a ULgrant with respect to a PUSCH to be transmitted on a specific UL CC istransmitted on a DL CC linked to the specific UL CC. In contrast, in amulti-carrier system, since a plurality of serving cells may beconfigured, transmission of the UL/DL grant on a serving cell having agood channel state may be permitted. Thus, if a cell in which the UL/DLgrant, which is scheduling information, is carried is different from acell in which UL/DL transmission corresponding to the UL/DL grant isperformed, this is called cross-carrier scheduling. 3GPP LTE(-A) maysupport an aggregate of plural CCs and support a cross-carrierscheduling operation based on the aggregated CCs, for improvement ofdata transmission rate and stable control signaling. In this case, oneCC (i.e., scheduled CC) may be pre-configured so as to receive DL/ULscheduling only from a specific single CC (i.e., scheduling CC) (i.e.,so as to receive a DL/UL grant PDCCH for a corresponding scheduled CC)and a corresponding scheduling CC may basically perform DL/UL schedulingthereof. For cross-carrier scheduling, a carrier indicator field (CIF)may be introduced. Whether the CIF is present or not in a PDCCH may besemi-statically and UE-specifically (or UE group-specifically)configured by higher layer signaling (e.g., RRC signaling).

One or more scheduling CCs may be configured per UE. A scheduling CC setmay be configured UE-specifically, UE group-specifically, orcell-specifically. The scheduling CC may be configured to directlyschedule at least itself. That is, the scheduling CC may be a scheduledCC thereof. Only one scheduling CC per scheduled CC may be configured.In other words, a plurality of scheduling CCs cannot be configured withrespect to one scheduled CC. In the present invention, a CC whichcarries a PDCCH is referred to as a scheduling CC, a monitoring CC, oran MCC and a CC which carries a PDSCH/PUSCH scheduled by the PDCCH isreferred to as a scheduled CC. The scheduling CC includes a DL CC as aportion of aggregated DL CCs. A UE detects/decodes the PDCCH only on theDL CC. That is, during cross-carrier scheduling, DL/UL grant PDCCHs forscheduling PDSCHs/PUSCHs of the scheduling CC and the scheduled CC maybe transmitted/received only through the scheduling CC. A DL ACK/NACKchannel (a PHICH in the case of 3GPP LTE(-A)) carrying ACK/NACK for aPUSCH transmitted on the scheduling CC or scheduled CC may betransmitted/received only on the scheduling CC. ACK/NACK for a PDSCHtransmitted on the scheduling CC or scheduled CC may betransmitted/received on a UL control channel (a PUCCH in the case of3GPP LTE(-A)) or a UL data channel (a PUSCH in the case of 3GPPLTE(-A)). As described earlier, according to current 3GPP LTE(-A)standards, the PUCCH may be transmitted/received on a PCC. Here, aPDSCH/PUSCH of a scheduling CC or scheduled CC refers to a PDSCH/PUSCHconfigured/allocated to be transmitted on a corresponding CC, andACK/NACK of a scheduling CC or scheduled CC refers to ACK/NACK for datatransmitted on a corresponding CC.

In 3GPP LTE-A of a next version (beyond LTE-A), an aggregate of pluralCCs present in different frequency bands is considered. Here, differentfrequency bands may mean different frequency bands having a very widefrequency spacing relative to bandwidth of one CC. In one frequencyband, a plurality of CCs each having a very narrow frequency spacingrelative to a spacing between the different frequency bands may bepresent. That is, CCs belonging to different frequency bands refer toCCs, center frequencies of which are separated. If CCs belonging todifferent frequency bands are aggregated, the UE has a high probabilityof operating an independent power amplifier per frequency band. If theUE operates an independent power amplifier per frequency band, ULtransmission can be efficiently performed even though a single carrierproperty required for UL transmission is only satisfied with respect toeach frequency band. Hereinafter, carrier aggregation using CCsbelonging to different frequency bands will be referred to asinter-frequency carrier aggregation and carrier aggregation using onlyCCs belonging to the same frequency band will be referred to asintra-frequency carrier aggregation.

In a 3GPP LTE(-A) system based on OFDM technology, time when a signaltransmitted by the UE arrives at the BS differs according to the radiusof a cell, location of the UE in the cell, and mobile speed of the UE.That is, if the BS does not manage a transmission timing of each UE, atransmission signal of a specific UE may cause interference with atransmission signal of another UE, thereby increasing an error rate of areception signal at the side of the BS. In terms of the BS, since dataor signals transmitted by all UEs in a cell should be received within aneffective time boundary in order to prevent influence of interference,the BS should appropriately adjust a transmission timing of a UEaccording to a situation of the UE. Such adjustment is called timingadvance maintenance or time alignment maintenance. One method formanaging UL time alignment is a random access procedure. That is,through the random access procedure, the BS receives a random accesspreamble transmitted by the UE and calculates a timing advance (TA)value for advancing or retarding the transmission timing of the UE usinginformation about the received random access preamble. The BS informsthe UE of the calculated TA value through a random access response andthe UE updates the transmission timing using the TA value. In a legacysystem, the random access procedure has been performed only on the PCC.In the case of inter-frequency carrier aggregation, since frequencycharacteristics differ according to a frequency band, a different TA perfrequency band may be provided in terms of UL synchronization.Accordingly, in the case of inter-frequency carrier aggregation, unlikethe legacy system in which the random access procedure is performed onlyon the PCC, the case may occur in which an additional random accessprocedure may be performed even with respect to an SCC present in afrequency band different from the PCC so that a UL transmission timingper frequency band should be adjusted. Further, even in the samefrequency, if antennas of different locations transmit/receive signalsusing the same frequency, the distance between the antennastransmitting/receiving the signals in the above frequency and a UEvaries with the antennas and thus one TA cannot be applied to a UL CCoperating in a frequency using the antennas of different locations.

Meanwhile, in TDD, most communication standards up to now consider onlyan aggregate of plural CCs having the same TDD DL-UL configuration.However, it is desirable to permit a different DL-UL configuration perCC in terms of efficient use of a communication link when difference inUL/DL load per CC and difference in channel state per CC are considered.If different DL-UL configurations are permitted, the number of DLsubframes and the number of UL subframes in a prescribed interval (e.g.a radio frame) per CC may differ and ACK/NACK timings configured on aPCC and an SCC, i.e. subframe timings at which ACK/NACK is transmittedon the PCC and the SCC, may differ. For example, in a specific subframe,while an ACK/NACK timing for the PCC may be configured as a UL subframe,an ACK/NACK timing for the SCC may be configured as a DL subframe, orvice versa. In addition, even when CCs having different TDD DL-ULconfigurations are aggregated, cross-carrier scheduling may besupported. In this case, UL grant and PHICH timings configured on ascheduling CC and a scheduled CC (i.e. DL subframe timings at which a ULgrant and a PHICH are transmitted) may differ. For example, a specificsubframe may be configured as a DL subframe, which is a UL grant orPHICH timing, with respect to the scheduling CC and as a UL subframewith respect to the scheduled CC, or vice versa. As a method for solvingthe difference in the UL/DL feedback timings, a method may be consideredfor redefining feedback transmission for an SCC/scheduled CC such thatfeedback transmission may be performed at a feedback timing configuredon a PCC/scheduling CC. However, feedback timing adjustment of theSCC/scheduled CC to the feedback timing configured on the PCC/schedulingCC is complicated in relationship configuration and may cause anasymmetric operation. Moreover, this method has a high probability ofentailing additional feedback delay.

If CCs operating in frequencies in different frequency bands areaggregated, if CCs operating in frequencies using antennas of differentlocations are aggregated, and/or if CCs having different TDD DL-ULconfigurations are aggregated, these UL CCs have different TAs accordingto a frequency characteristic or a UL timing characteristic. To supporta plurality of UL TAs, the present invention groups the CCs(hereinafter, CC groups) according to the frequency characteristic or ULtiming characteristic and manages a TA per CC group. In other words,according to the present invention, all aggregated CCs are classifiedinto a plurality of CC groups based on frequency bands, TDD DL-ULconfigurations, and/or antenna locations and one UL anchor CC per CCgroup is configured. According to the present invention, one UE forwhich carrier aggregation is configured may have at least a PCC groupand, if SCC(s) having a TA different from that of the PCC is present,the UE may have one or more SCC groups together with a PCC group. ThePCC group may include at least a PCC and may or may not include an SCC.Each SCC group may include one or more SCCs.

In a PCC group, a PCC becomes a UL anchor CC. In an SCC group, any oneof one or more SCCs belonging to the SCC group may be configured as theUL anchor CC. Upon adding an SCC as a serving CC for the UE, informationindicating whether the SCC is the UL anchor CC may be transmitted to theUE. Alternatively, information indicating an anchor CC among SCCsconfigured for the UE may be transmitted to the UE. The BS may indicatewhether a normal SCC other than an anchor SCC belongs to a PCC group oran SCC group to the UE. If the normal SCC belongs to the SCC group, theBS may informs the UE of which SCC group the normal SCC belongs to.

In order for the UE to manage a TA per CC group, in an embodiment of thepresent invention, a random access preamble (hereinafter, RACH preamble)may be independently allocated per UL anchor CC. Then the UE may performa random access procedure (hereinafter, RACH procedure) per CC group.Hence, according to an embodiment of the present invention, the UEperforms the RACH procedure on an SCC as well as a PCC. Morespecifically, the RACH procedure may be performed through a CCconfigured as a UL anchor CC (in TDD) or through a DL CC (in FDD) linkedto the UL anchor CC. Alternatively, the RACH procedure may be performedthrough UL transmission (e.g. an RACH preamble, a PUSCH based on arandom access response, etc.) using the UL anchor CC and through DLtransmission (e.g. a PDCCH order, a random access response, etc.) usingthe PCC.

As opposed to a legacy wireless system in which the same TA is appliedto all UL CCs, different TAs are applied to different CC groups in thepresent invention. Accordingly, if a PUCCH for all serving CCs istransmitted only on the PCC, the case may occur in which the BS cannotcorrectly obtain channel state information (CSI) associated with servingCC(s) which does not belong to a PCC group, HARQ feedback, andscheduling request information. Therefore, the present inventionproposes an embodiment for transmitting/receiving a PUCCH for CC(s)belonging to each CC group on a UL anchor CC configured in acorresponding CC group.

Namely, according to the present invention, a PCC is used for PUCCHtransmission(s) only for a PCC group and an SCC configured as a ULanchor CC is used for PUCCH transmission for an SCC group to which theSCC belongs. Then, the UE transmits UCI associated with serving CC(s)belonging to a PCC group to the BS through a PUCCH of a PCC andtransmits UCI associated with serving CC(s) of an SCC group to which anSCC belongs to the BS through a PUCCH of the SCC configured as the ULanchor CC. That is, according to the present invention, the UE maytransmit the PUCCH on a CC configured as the UL anchor CC as well as onthe PCC and the BS may receive the PUCCH on the SCC as well as on thePCC. A detailed description of characteristics related to ACK/NACKtransmission through the PUCCH of the UL anchor CC is as follows.

-   -   For ACK/NACK transmission, an implicit PUCCH (format 1a/1b)        resource, which is linked to a CCE resource of a UL anchor CC        (in TDD) or a DL CC (in FDD) linked to the UL anchor CC, and an        additional explicit PUCCH (format 1a/1b/3) resource may be        defined on the UL anchor CC. In other words, the explicit and/or        implicit PUCCH resources may be reserved on the UL anchor CC. In        an embodiment of the present invention, if a UE operating in TDD        receives only a PDCCH/PDSCH carrying a specific DL grant        (hereinafter, a DL grant PDCCH/PDSCH) for a CC configured as a        UL anchor CC, the UE may transmit ACK/NACK information for the        DL grant PDCCH/PDSCH to the BS using the implicit PUCCH resource        implicitly determined by linkage with an index of a resource        unit (e.g. CCE) in the DL grant PDCCH. In this case, the        specific DL grant may be DCI which schedules DL transmission        using the UL anchor CC, wherein a downlink assignment index        (DAI) of the specific DL grant is configured as 1. If a DAI        V^(DL) _(DAI) for DL transmission is detected in a specific        subframe n, the DAI indicates the number of subframes having        PDCCH and PDSCH transmission indicating DL semi-persistent        scheduling (SPS) release among a prescribed number of        subframe(s) up to the specific subframe n. For example, if the        UE receives only a PDCCH carrying DAI set to 1, the UE may        transmit ACK/NACK information for a DL grant PDCCH/PDSCH        corresponding to the DAI set to 1 to the BS using a PUCCH        resource linked to a PDCCH. Meanwhile, in the embodiment of the        present invention, if a UE operating in FDD receives only a DL        grant PDCCH/PDSCH for a DL CC linked to a UL anchor CC, the UE        may transmit ACK/NACK for the DL grant PDCCH/PDSCH to the BS        using an implicit PUCCH resource implicitly determined by        linkage with the DL grant PDCCH.    -   A transmit power control (TPC) field in a DL grant PDCCH may be        used for PUCCH power control information and ACK/NACK resource        selection information. In an embodiment of the present        invention, a TPC field is independently utilized per CC group.        For example, in TDD, a TPC field included in a specific PDCCH        for scheduling a UL anchor CC may be used for power control for        PUCCH transmission on the UL anchor CC and TPC fields included        in all other PDCCHs for scheduling a CC group to which the UL        anchor CC belongs may be used for explicit indication of a PUCCH        resource to be used for ACK/NACK transmission for the CC group        among PUCCH resources reserved for the UL anchor CC. In this        case, the specific PDCCH may be a PDCCH carrying a DAI set to 1.        As another example, in FDD, a TPC field included in a PDCCH for        scheduling a DL CC linked to a UL anchor CC may be used for        power control for PUCCH transmission on the UL anchor CC and TPC        fields included in all other PDCCHs for scheduling a CC group to        which the UL anchor CC belongs may be used for explicit        indication of a PUCCH resource to be used for ACK/NACK        transmission for the CC group among PUCCH resources reserved for        the UL anchor CC. According to this embodiment, a UL anchor CC        of an SCC group, which is an SCC, is different from a        conventional SCC in that PUCCH transmit power is controlled by        TPC.

As mentioned above, in the present invention, the UL anchor CC is incharge of PUCCH transmission of ACK/NACK and/or CSI for a CC group towhich the CC belongs. Accordingly, in the present invention, a UL anchorCC or a DL CC linked to the UL anchor CC is activated most quickly andis deactivated most slowly among all CCs in a CC group to which the ULanchor CC belongs. In the case of cross-carrier scheduling, the BS mayconfigure CCs such that the relationship between a scheduling CC (MCC)and a scheduled CC is formed only in a CC group. In other words, the BSmay perform scheduling such that a scheduling CC and a scheduled CCscheduled by the scheduling CC may belong to the same CC group. Duringcross-carrier scheduling, the BS may configure a UL anchor CC always asthe scheduling CC in TDD and configure a DL CC linked to the UL anchorCC always as the scheduling CC in FDD.

Meanwhile, if a scheduled PUSCH is present at a PUCCH transmissiontiming, that is, if a transmission time of a PUCCH carrying UCI such asACK/NACK and/or periodic CSI is a subframe to which a PUSCH isallocated, the UCI is transmitted/received by piggybacking the same onthe PUSCH. In this case, according to an embodiment of the presentinvention, the UE transmits UCI for each CC group to the BS only througha PUSCH allocated to one of UL CC(s) in the CC group. That is, if thetransmission timing of a PUCCH using a UL anchor CC in a CC groupcollides with the transmission timing of a PUSCH using one CC in the CCgroup, the UE drops PUCCH transmission and transmits UCI for the CCgroup to the BS even on the PUSCH. Even in the case of aperiodic CSItransmission through the PUSCH, the UE may transmit CSI for a target CCof aperiodic CSI reporting to the BS only on a PUSCH allocated to one ofUL CC(s) of a CC group to which the target CC belongs. That is, UCIassociated with CC(s) belonging to a PCC group is transmitted/receivedon a PUCCH of a PCC or transmitted/received on a PUSCH of the PCC or aPUSCH of an SCC. UCI associated with CC(s) belonging to an SCC group istransmitted/received on a PUCCH of an SCC configured as a UL anchor CCor transmitted/received on a PUSCH scheduled on an arbitrary SCC.

FIGS. 7 and 8 illustrate embodiments of the present invention.Particularly, FIG. 7 illustrates a method for transmitting/receiving aDL grant and ACK/NACK for the DL grant according to an embodiment of thepresent invention and FIG. 8 illustrates a method fortransmitting/receiving a UL grant and ACK/NACK for the UL grantaccording to an embodiment of the present invention. For reference, itis assumed in FIGS. 7 and 8 that there is no delay between reception ofa DL/UL grant, reception/transmission of DL/UL data, and transmission ofa DL/UL feedback signal.

Referring to FIGS. 7 and 8, in CC group 1, two DL subframes correspondto one UL subframe and, in CC group 2, three DL subframes correspond toone UL subframe. That is, in CC group 1, a UE transmits ACK/NACKinformation for DL data received in two DL subframes to a BS in a ULsubframe corresponding to the two DL subframes and, in CC group 2, theUE transmits ACK/NACK information for DL data received in three DLsubframes to the BS in a UL subframe corresponding to the three DLsubframes. A UL anchor CC is configured per CC group. Duringcross-carrier scheduling, the UL anchor CC may be configured as an MCCcarrying DL/UL scheduling information for all or some CCs in a CC groupto which the UL anchor CC belongs. In examples illustrated in FIGS. 7and 8, the UL anchor CC is configured as the MCC.

Referring to FIG. 7, the BS may transmit a DL grant (i.e. PDSCHscheduling) and a PDSCH for the DL grant to the UE in a DL subframe andreceive ACK/NACK information for a PDCCH carrying the DL grant and/or aPDSCH scheduled by the PDCCH from the UE in a UL subframe associated tothe DL subframe (e.g. a UL subframe a prescribed number of subframesafter the DL subframe). The UE according to the present inventiontransmits ACK/NACK information for the PDCCH or the PDSCH scheduled bythe PDCCH to the BS on a CC group basis. Referring to FIG. 7, the UE maytransmit ACK/NACK information for PDCCHs and/or PDSCHs received on CC1and CC2, which are CCs of CC group 1, to the BS through a PUCCH on CC1configured as a UL anchor CC out of CC1 and CC2. If there is a CC towhich a PUSCH colliding with a PUCCH transmission timing is allocated,among CCs of CC group 1, the UE may transmit ACK/NACK informationregarding CC group 1 to the BS by piggybacking the same on a PUSCHallocated to one CC of CC group 1. Similarly, the UE may transmitACK/NACK information for PDCCHs and/or PDSCHs received on CC3 and CC4,which are CCs of CC group 2, to the BS through a PUCCH on CC3 configuredas a UL anchor CC out of CC3 and CC4. If there is a CC to which a PUSCHcolliding with a PUCCH transmission timing is allocated, among CCs of CCgroup 2, the UE may transmit ACK/NACK information regarding CC group 2to the BS by piggybacking the same on a PUSCH allocated to one CC of CCgroup 2.

Referring to FIG. 8, the BS may transmit a UL grant (i.e. PUSCHscheduling) to the UE in a DL subframe and receive a PUSCH according tothe UL grant from the UE in a UL subframe associated to the DL subframe(e.g. a UL subframe a prescribed number of subframes after the DLsubframe). The BS may transmit a PHICH carrying ACK/NACK for the PUSCHto the UE in a DL subframe associated with a UL subframe in which thePUSCH is received (e.g. a DL subframe a prescribed number of subframesafter the UL subframe). The BS according to the present inventiontransmits ACK/NACK information for the PUSCH to the UE on a CC groupbasis and the UE receives the ACK/NACK information for the PUSCH fromthe BS on a CC group basis. Referring to FIG. 8, the BS may transmitACK/NACK information for PUSCH(s) received on CC1 and CC2, which are CCsof CC group 1, to the UE through a PHICH on CC1 configured as a ULanchor CC out of CC1 and CC2 and the UE may receive a PHICH carrying theACK/NACK information for the PUSCH(s) transmitted using CC(s) of CCgroup 1 from the BS on CC1 configured as an anchor CC of CC group 1.Similarly, the BS may transmit ACK/NACK information for PUSCH(s)received on CC3 and CC4, which are CCs of CC group 2, to the UE througha PHICH on CC3 configured as a UL anchor CC out of CC3 and CC4 and theUE may receive a PHICH carrying the ACK/NACK information for thePUSCH(s) transmitted using CC(s) of CC group 2 from the BS on CC3configured as an anchor CC of CC group 2.

ACK/NACK transmission timings for DL/UL transmission illustrated inFIGS. 7 and 8 are purely exemplary and may be differently configuredaccording to FDD mode or non-FDD mode and/or according to TDD UL-DLconfiguration.

FIG. 9 is a block diagram illustrating elements of a transmitting device10 and a receiving device 20 for implementing the present invention.

The transmitting device 10 and the receiving device 20 respectivelyinclude Radio Frequency (RF) units 13 and 23 capable of transmitting andreceiving radio signals carrying information, data, signals, and/ormessages, memories 12 and 22 for storing information related tocommunication in a wireless communication system, and processors 11 and21 operationally connected to elements such as the RF units 13 and 23and the memories 12 and 22 to control the elements and configured tocontrol the memories 12 and 22 and/or the RF units 13 and 23 so that acorresponding device may perform at least one of the above-describedembodiments of the present invention.

The memories 12 and 22 may store programs for processing and controllingthe processors 11 and 21 and may temporarily store input/outputinformation. The memories 12 and 22 may be used as buffers.

The processors 11 and 21 generally control the overall operation ofvarious modules in the transmitting device and the receiving device.Especially, the processors 11 and 21 may perform various controlfunctions to implement the present invention. The processors 11 and 21may be referred to as controllers, microcontrollers, microprocessors, ormicrocomputers. The processors 11 and 21 may be implemented by hardware,firmware, software, or a combination thereof. In a hardwareconfiguration, application specific integrated circuits (ASICs), digitalsignal processors (DSPs), digital signal processing devices (DSPDs),programmable logic devices (PLDs), or field programmable gate arrays(FPGAs) may be included in the processors 11 and 21. Meanwhile, if thepresent invention is implemented using firmware or software, thefirmware or software may be configured to include modules, procedures,functions, etc. performing the functions or operations of the presentinvention. Firmware or software configured to perform the presentinvention may be included in the processors 11 and 21 or stored in thememories 12 and 22 so as to be driven by the processors 11 and 21.

The processor 11 of the transmitting device 10 performs predeterminedcoding and modulation for a signal and/or data scheduled to betransmitted to the outside by the processor 11 or a scheduler connectedwith the processor 11, and then transfers the coded and modulated datato the RF unit 13. For example, the processor 11 converts a data streamto be transmitted into K layers through demultiplexing, channel coding,scrambling, and modulation. The coded data stream is also referred to asa codeword and is equivalent to a transport block which is a data blockprovided by a MAC layer. One transport block (TB) is coded into onecodeword and each codeword is transmitted to the receiving device in theform of one or more layers. For frequency up-conversion, the RF unit 13may include an oscillator. The RF unit 13 may include N_(t) (where N_(t)is a positive integer) transmit antennas.

A signal processing process of the receiving device 20 is the reverse ofthe signal processing process of the transmitting device 10. Undercontrol of the processor 21, the RF unit 23 of the receiving device 20receives radio signals transmitted by the transmitting device 10. The RFunit 23 may include N_(r) receive antennas and frequency down-convertseach signal received through receive antennas into a baseband signal.The processor 21 decodes and demodulates the radio signals receivedthrough the receive antennas and restores data that the transmittingdevice 10 intended to transmit.

The RF units 13 and 23 include one or more antennas. An antenna performsa function of transmitting signals processed by the RF units 13 and 23to the exterior or receiving radio signals from the exterior to transferthe radio signals to the RF units 13 and 23, according to an embodimentof the present invention under control of the processors 11 and 21. Theantenna may also be called an antenna port. Each antenna may correspondto one physical antenna or may be configured by a combination of morethan one physical antenna element. The signal transmitted from eachantenna cannot be further deconstructed by the receiving device 20. AnRS transmitted in correspondence to a corresponding antenna defines anantenna viewed from the receiving device 20 and enables the receivingdevice 20 to perform channel estimation for the antenna, irrespective ofwhether it is a single radio channel from one physical antenna or acomposite channel from a plurality of physical antenna elementsincluding the antenna. In other words, the antenna is defined such thata channel carrying a symbol of the antenna may be obtained from achannel carrying another symbol of the same antenna. An RF unitsupporting a MIMO function of transmitting and receiving data using aplurality of antennas may be connected to two or more antennas.

In the embodiments of the present invention, a UE operates as thetransmitting device 10 in UL and as the receiving device 20 in DL. Inthe embodiments of the present invention, a BS operates as the receivingdevice 20 in UL and as the transmitting device 10 in DL. In theembodiments of the present invention, the processor, RF unit, and memoryincluded in the UE will be referred to as a UE processor, a UE RF unit,and a UE memory, respectively, and the processor, RF unit, and memoryunit included in the BS will be referred to as a BS processor, a BS RFunit, and a BS memory, respectively.

According to the embodiments of the present invention, the BS processorcontrols the BS RF unit to transmit a PDCCH, a PDSCH, and a PHICH andthe UE processor controls the UE RF unit to receive the PDCCH, thePDSCH, and the PHICH. According to the embodiments of the presentinvention, the UE processor controls the UE RF unit to transmit a PUCCHand a PUSCH and the BS processor controls the BS RF unit to receive thePUCCH and the PUSCH.

Specifically, the BS processor classifies CCs configured for the UE intoa plurality of CC groups based on frequency bands, TDD DL-ULconfigurations, and/or antenna locations and configures one UL anchor CCper CC group. Then, the CCs configured for the UE, i.e. serving CCs ofthe UE, may be divided into at least one PCC group and zero or more SCCgroups. The BS processor and the UE processor may configure a PCC as aUL anchor CC of a PCC group. The BS processor may configure one SCC perSCC group as a UL anchor CC and control the BS RF unit to transmitinformation about a UL anchor CC per SCC group. The UE processor mayconfigure a UL anchor CC per SCC group based on information about the ULanchor CC. Upon adding an SCC as a serving CC for the UE, the BSprocessor may control the BS RF unit to transmit information indicatingwhether the SCC is the UL anchor CC to the UE. Alternatively, the BSprocessor may control the BS RF unit to transmit information indicatingan anchor CC among SCCs configured for the UE to the UE. Alternatively,the BS processor may control the BS RF unit to transmit informationindicating whether a normal SCC other than an anchor SCC belongs to aPCC group or an SCC group to the UE and, if the normal SCC belongs tothe SCC group, the BS processor may control the BS RF unit to indicateto which SCC group the normal SCC belongs to the UE.

In order for the UE processor to manage a TA per CC group, in anembodiment of the present invention, a random access preamble(hereinafter, RACH preamble) may be independently allocated per ULanchor CC. Then the UE may perform a random access procedure(hereinafter, RACH procedure) per CC group. Hence, according to anembodiment of the present invention, the UE performs the RACH procedureper CC group. Hence, according to an embodiment of the presentinvention, the UE processor may perform the RACH procedure on an SCC aswell as a PCC. The UE processor may control the UE RF unit to performthe RACH procedure through a CC configured as a UL anchor CC (in TDD) orthrough a DL CC (in FDD) linked to the UL anchor CC. Alternatively, theUE processor may control the UE RF unit to perform UL transmission (e.g.an RACH preamble, a PUSCH based on a random access response, etc.) tothe BS using a UL anchor CC and control the UE RF unit to perform DLtransmission (e.g. a PDCCH order, a random access response, etc.) fromthe BS using the PCC, thereby performing an RACH procedure per CC group.

The UE processor according to the present invention controls the UE RFunit to transmit a PUCCH for CC(s) belonging to each CC group on a ULanchor CC configured for a corresponding CC group and the BS processorcontrols the BS RF unit to receive the PUCCH for the CC(s) belonging toeach CC group on the UL anchor CC configured for the corresponding CCgroup. The UE processor controls the UE RF unit to transmit UCIassociated with serving CC(s) belonging to a PCC group to the BS througha PUCCH of a PCC and controls UE RF unit to transmit the UCI associatedwith serving CC(s) of an SCC group to which an SCC configured as a ULanchor CC belongs to the BS through a PUCCH of the SCC. The BS processorcontrols the BS RF unit to receive the UCI associated with the servingCC(s) belonging to the PCC group from the UE through the PUCCH of thePCC and controls the BS RF unit to receive the UCI associated with theserving CC(s) of the SCC group to which the SCC configured as the ULanchor CC belongs from the UE through the PUCCH of the SCC.

In an embodiment of the present invention, if the UE RF unit operatingin TDD receives only a PDCCH/PDSCH carrying a specific DL grant(hereinafter, a DL grant PDCCH/PDSCH) for a CC configured as a UL anchorCC, the UE processor may control the UE RF unit to transmit ACK/NACKinformation for the DL grant PDCCH/PDSCH to the BS using an implicitPUCCH resource implicitly determined by linkage with an index of aresource unit (e.g. a CCE) in the DL grant PDCCH. In this case, thespecific DL grant may be DCI which schedules DL transmission using a ULanchor CC, wherein a DAI of the specific DL grant is set to 1. In anembodiment of the present invention, if the UE RF unit operating in FDDreceives only a DL grant PDCCH/PDSCH for a DL CC linked to a UL anchorCC, the UE processor may control the UE RF unit to transmit ACK/NACKinformation for the DL grant PDCCH/PDSCH to the BS using an implicitPUCCH resource implicitly determined by linkage with the DL grant PDCCH.

The BS processor and the UE processor according to an embodiment of thepresent invention independently use a TPC field per CC group. Forexample, in TDD, the BS processor may use a TPC field included in aspecific PDCCH that schedules a UL anchor CC to perform power controlfor PUCCH transmission on the UL anchor CC and use TPC fields includedin all other PDCCHs that schedule a CC group to which the UL anchor CCbelongs to explicitly indicate a PUCCH resource to be used for ACK/NACKtransmission for the CC group among PUCCH resources reserved for the ULanchor CC. In this case, the specific PDCCH may be a PDCCH carrying aDAI set to 1. As another example, in FDD, the BS processor may use a TPCfield included in a PDCCH that schedules a DL CC linked to a UL anchorCC to perform power control for PUCCH transmission on the UL anchor CCand use TPC fields included in all other PDCCHs that schedule a CC groupto which the UL anchor CC belongs to explicitly indicate a PUCCHresource to be used for ACK/NACK transmission for the CC group amongPUCCH resources reserved for the UL anchor CC. The UE RF unit receivesDCI including the TPC field and transmits the DCI to the UE processor.If the DCI including the TPC field is scheduling information for the ULanchor CC, the UE processor may use a value of the TPC field todetermine a PUCCH transmit power on the UL anchor CC and, if the DCIincluding the TPC field is scheduling information for an SCC other thanthe UL anchor CC, the UE processor may use the value of the TPC field todetermine a PUCCH resource to be used for transmission of ACK/NACKinformation for a CC group to which the UL anchor CC belongs among PUCCHresources reserved for the UL anchor CC.

In an embodiment of the present invention, the BS processor may mostquickly activate or most slowly deactivate a UL anchor CC or a DL CClinked to the UL anchor CC among all CCs in a CC group to which the ULanchor CC belongs. In the case of cross-carrier scheduling, the BSprocessor may perform scheduling such that a scheduling CC and ascheduled CC scheduled by the scheduling CC belong to the same CC group.During cross-carrier scheduling, the BS processor may configure a ULanchor CC always as the scheduling CC in TDD and configure a DL CClinked to the UL anchor CC always as the scheduling CC in FDD.

Meanwhile, if a scheduled PUSCH is present at a PUCCH transmissiontiming, that is, if a transmission time point of a PUCCH carrying UCIsuch as ACK/NACK and/or periodic CSI is a subframe to which a PUSCH isallocated, the UE processor may control the UE RF unit to transmit theUCI by piggybacking the same on the PUSCH and the BS processor maycontrol the BS RF unit to receive the PUSCH and decode the UCI from thePUSCH. In this case, according to an embodiment of the presentinvention, the UE processor may control the UE RF unit to transmit UCIfor each CC group to the BS only through a PUSCH allocated to one of ULCC(s) in a corresponding CC group and the BS processor may determine theUCI received on the PUSCH of one CC to be UCI for a CC group to whichthe CC belongs. Even in the case of aperiodic CSI transmission throughthe PUSCH, the UE processor may control the UE RF unit to transmit CSIfor a target CC of aperiodic CSI reporting to the BS only on a PUSCHallocated to one of UL CC(s) of a CC group to which the target CCbelongs and the BS processor may determine CSI reporting received on thePUSCH of one CC to be CSI for a CC group to which the CC belongs. Thatis, UCI associated with CC(s) belonging to a PCC group istransmitted/received on a PUCCH of a PCC or transmitted/received on aPUSCH of the PCC or a PUSCH of an SCC. UCI associated with CC(s)belonging to an SCC group is transmitted/received on a PUCCH of an SCCconfigured as a UL anchor CC or transmitted/received on a PUSCHscheduled on an arbitrary SCC.

According to the present invention described hereinabove, UL CCs onwhich the UE and the BS operate in different frequencies and/or UL CC(s)on which the UE and the BS operate in a frequency using antennas ofdifferent locations can be aggregated and a plurality of timesynchronizations for one UE can be efficiently managed. In addition,according to the present invention, different time synchronizations maybe applied to UL CCs having different frequency characteristics.Furthermore, DL/UL control information can be efficientlytransmitted/received in a carrier aggregation environment and across-carrier scheduling environment.

The detailed description of the preferred embodiments of the presentinvention has been given hereinabove to enable those skilled in the artto implement and practice the invention. Although the invention has beendescribed with reference to exemplary embodiments, those skilled in theart will appreciate that various modifications and variations can bemade in the present invention without departing from the spirit andscope of the invention described in the appended claims. Accordingly,the invention should not be limited to the specific embodimentsdescribed herein, but should be accorded the broadest scope consistentwith the principles and novel features disclosed herein.

The embodiments of the present invention are applicable to a BS, a UE,or other devices in a wireless communication system.

What is claimed is:
 1. A method for receiving, by a base station, uplinksignals from a user equipment, the method comprising: transmitting, bythe base station, scheduling cell information indicating which cell is ascheduling cell for a cell which is one of a plurality of serving cellsfor the user equipment; transmitting, by the base station, a physicaldownlink control channel (PDCCH) carrying an uplink grant for the cellthrough the scheduling cell among the plurality of serving cells basedon the scheduling cell information; and receiving, by the base station,a physical uplink shared channel (PUSCH) carrying uplink data of theuser equipment through the cell according to the uplink grant, whereinthe user equipment is configured with at least a primary cell (PCell)group and a secondary cell (SCell) group, wherein the PCell group isconfigured with a PCell and zero or more SCells among the plurality ofserving cells, and the SCell group is configured with one or more SCellsnot belonging to the PCell group among the plurality of serving cells,wherein the cell belongs to the PCell group or the SCell group, andwherein the scheduling cell information indicates part of the same PCellor SCell group to which the cell belongs, as the scheduling cell for thecell.
 2. The method according to claim 1, further comprising:transmitting, by the base station, a PDCCH carrying a downlink grant forthe SCell group; and receiving, by the base station, a physical uplinkcontrol channel (PUCCH) carrying acknowledgement/negativeacknowledgement (ACK/NACK) information for the SCell group from the userequipment, wherein the PUCCH is received on an SCell configured as ananchor SCell among the one or more SCells belonging to the SCell group.3. The method according to claim 2, wherein the PUCCH is received usinga PUCCH resource associated with a control channel element (CCE) of thePDCCH carrying the downlink grant, when the downlink grant is for theanchor SCell and the ACK/NACK information is only for the anchor SCell,and wherein the PUCCH is received using a PUCCH resource determinedbased on a transmit power control (TPC) field included in the PDCCHcarrying the downlink grant, when the downlink grant is for an SCellother than the anchor SCell among the one or more SCells belonging tothe SCell group.
 4. A base station for receiving uplink signals from auser equipment, the base station comprising: a radio frequency (RF)unit, and a processor configured to: control the RF unit to transmitscheduling cell information indicating which cell is a scheduling cellfor a cell which is one of a plurality of serving cells for the userequipment, control the RF unit to transmit a physical downlink controlchannel (PDCCH) carrying an uplink grant for the cell through thescheduling cell among the plurality of serving cells based on thescheduling cell information, and control the RF unit to receive aphysical uplink shared channel (PUSCH) carrying uplink data through thecell according to the uplink grant, wherein the user equipment isconfigured with at least a primary cell (PCell) group and a secondarycell (SCell) group, wherein the PCell group is configured with a PCelland zero or more SCells among the plurality of serving cells, and theSCell group is configured with one or more SCells not belonging to thePCell group among the plurality of serving cells, wherein the cellbelongs to the PCell group or the SCell group, and wherein thescheduling cell information indicates part of the same PCell or SCellgroup to which the cell belongs, as the scheduling cell for the cell. 5.The base station according to claim 4, wherein the processor controlsthe RF unit to transmit a PDCCH carrying a downlink grant for the SCellgroup, wherein the processor controls the RF unit to receive a physicaluplink control channel (PUCCH) carrying acknowledgement/negativeacknowledgement (ACK/NACK) information for the SCell group from the userequipment, and wherein the PUCCH is received on an SCell configured asan anchor SCell among the one or more SCells belonging to the SCellgroup.
 6. The base station according to claim 5, wherein the PUCCH isreceived using a PUCCH resource associated with a control channelelement (CCE) of the PDCCH carrying the downlink grant, when thedownlink grant is for the anchor SCell and the ACK/NACK information isonly for the anchor SCell, and wherein the PUCCH is received using aPUCCH resource determined based on a transmit power control (TPC) fieldincluded in the PDCCH carrying the downlink grant, when the downlinkgrant is for an SCell other than the anchor SCell among the one or moreSCells belonging to the SCell group.
 7. A method for transmitting, by auser equipment, uplink signals, the method comprising: receiving, by theuser equipment, scheduling cell information indicating which cell is ascheduling cell for a cell which is one of a plurality of serving cellsfor the user equipment; receiving, by the user equipment, a physicaldownlink control channel (PDCCH) carrying an uplink grant for the cellthrough the scheduling cell among the plurality of serving cells basedon the scheduling cell information; and transmitting, by the userequipment, a physical uplink shared channel (PUSCH) carrying uplink datathrough the cell according to the uplink grant, wherein the userequipment is configured with at least a primary cell (PCell) group and asecondary cell (SCell) group, wherein the PCell group is configured witha PCell and zero or more SCells among the plurality of serving cells,and the SCell group is configured with one or more SCells not belongingto the PCell group among the plurality of serving cells, wherein thecell belongs to the PCell group or the SCell group, and wherein thescheduling cell information indicates part of the same PCell or SCellgroup to which the cell belongs, as the scheduling cell for the cell. 8.The method according to claim 7, further comprising: receiving, by theuser equipment, a PDCCH carrying a downlink grant for the SCell group;and transmitting, by the user equipment, a physical uplink controlchannel (PUCCH) carrying acknowledgement/negative acknowledgement(ACK/NACK) information for the SCell group, wherein the PUCCH istransmitted on an SCell configured as an anchor SCell among the one ormore SCells belonging to the SCell group.
 9. The method according toclaim 8, wherein the PUCCH is transmitted using a PUCCH resourceassociated with a control channel element (CCE) of the PDCCH carryingthe downlink grant, when the downlink grant is for the anchor SCell andthe ACK/NACK information is only for the anchor SCell, and wherein thePUCCH is transmitted using a PUCCH resource determined based on atransmit power control (TPC) field included in the PDCCH the downlinkgrant, when the downlink grant is for an SCell other than the anchorSCell among the one or more SCells belonging to the SCell group.
 10. Themethod according to claim 8, further comprising: adjusting uplinktransmission timing for the PCell group based on a random accessprocedure using the PCell; and adjusting uplink transmission timing forthe SCell group based on a random access procedure using the anchorSCell.
 11. A user equipment for transmitting uplink signals, the userequipment comprising: a radio frequency (RF) unit, and a processorconfigured to: control the RF unit to receive scheduling cellinformation indicating which cell is a scheduling cell for a cell whichis one of a plurality of serving cells for the user equipment, controlthe RF unit to receive a physical downlink control channel (PDCCH)carrying an uplink grant for the cell through the scheduling cell amongthe plurality of serving cells based on the scheduling cell information,and control the RF unit to receive a physical uplink shared channel(PUSCH) carrying uplink data through the cell according to the uplinkgrant, wherein the user equipment is configured with at least a primarycell (PCell) group and a secondary cell (SCell) group, wherein the PCellgroup is configured with a PCell and zero or more SCells among theplurality of serving cells, and the SCell group is configured with oneor more SCells not belonging to the PCell group among the plurality ofserving cells, wherein the cell belongs to the PCell group or the SCellgroup, and wherein the scheduling cell information indicates part of thesame PCell or SCell group to which the cell belongs, as the schedulingcell for the cell.
 12. The user equipment according to claim 11, whereinthe processor controls the RF unit to receive a PDCCH carrying adownlink grant for the SCell group, wherein the processor controls theRF unit to transmit a physical uplink control channel (PUCCH) carryingacknowledgement/negative acknowledgement (ACK/NACK) information for theSCell group, and wherein the PUCCH is transmitted on an SCell configuredas an anchor SCell among the one or more SCells belonging to the SCellgroup.
 13. The user equipment according to claim 12, wherein the PUCCHis transmitted using a PUCCH resource associated with a control channelelement (CCE) of the PDCCH carrying the downlink grant, when thedownlink grant is for the anchor SCell and the ACK/NACK information isonly for the anchor SCell, and wherein the PUCCH is transmitted using aPUCCH resource determined based on a transmit power control (TPC) fieldincluded in the PDCCH carrying the downlink grant, when the downlinkgrant is for an SCell other than the anchor SCell among the one or moreSCells belonging to the SCell group.
 14. The user equipment according toclaim 12, wherein the processor adjusts uplink transmission timing forthe PCell group based on a random access procedure using the PCell andadjusts uplink transmission timing for the SCell group based on a randomaccess procedure using the anchor SCell.